1. Field of the Invention
The present invention relates to an energy-saving solar air conditioning system for buildings. Particularly, the present invention relates to an energy-saving air conditioning system by which, in winter, the preheated air will be introduced into buildings; and in summer, the hot indoor air will be expelled out of the buildings and fresh air will be guided into the buildings.
2. Description of the Related Art
With increasing CO2 emissions, the global climate has become abnormal and ecological destruction has increased greatly. As a result, industrialized countries have again become aware of the urgency to reduce their dependence on fossil fuels after the energy crisis in the 70's. Consequently, these countries have given positive comments on how to use solar energy more effectively. Though the technology field still has reservations about whether solar energy will be able to replace other energy resources in the near future, one thing that is almost certain is that solar energy will be playing a very important role in a number of fields, especially those related to domestic heating and air ventilation.
As far as an air conditioning system using solar energy for domestic heating and air ventilation is concerned, a solar collector is the key device for the system, and it has to be mounted at an outdoor location where sufficient sunlight can be collected, such as on a roof or wall. In the past, a lot of effort has been made in developing solar collectors with different functions and styles. Many of them have been disclosed in patent literature. The most typical example is glazing a glass panel or transparent panel onto a fixed outer frame of a heat-insulated chamber and passing fluid through black heat-absorbing plates or pipes installed inside the chamber, so as to absorb the solar energy. Examples include the solar hot water supply system disclosed in U.S. Pat. No. 4,418,685, the air ventilation facility disclosed in WO9,625,632, the roof-style air ventilation facility disclosed in US2002/0,032,000A1, and the wall-style air preheater disclosed in U.S. Pat. No. 4,934,338. However, the solar collectors used presently still have some drawbacks. Therefore, there is much room for improvements in applying and promoting the usage of solar energy to save energy and facilitate air conditioning in buildings. The aforementioned drawbacks include:
(1) The conventional solar collector is too heavy. Its long-term use may cause a load to some buildings.
(2) The structure of the conventional solar collector is complicated, which makes its installation and maintenance difficult. Moreover, it increases the costs and thus prolongs the return period.
(3) The conventional solar heating device has poor compatibility and flexibility to match every type of buildings. Very often, it has to be custom-made.
(4) The contour of the solar collector is obtrusive and often impairs the aesthete and harmony of the overall appearance of the buildings.
(5) The package of the collector takes up much space and increases the costs for storage, commodity display, and channel marketing.
(6) The integral assembly of the whole-unit product is bulky, making it difficult for the application on a large area and increases installation cost.
(7) Glass or transparent panels are glazed onto the outer frame of a heat-insulated chamber. Different thermal expansion coefficients of materials may cause thermal stress problems.
(8) The conventional design cannot satisfy clients' senses of participation and achievement by self-installing the collectors.
(9) Some of the conventional designs can only be applicable to the buildings which are under construction and well-planned for its installation. For most existing buildings, the designs are unsuitable.
(10) When air passes over a glazed panel, heat is dissipated unless a double-glazing is used, but it is expensive and troublesome.
(11) Hot water supply systems or liquid systems operated by solar heating have the problems due to potential of freezing and leakage which impede to reach the expected performance.